BRUSSELS — Weeks after being berated by U.S. President Donald Trump for failing to spend enough on defense, European nations vowed Thursday to boost military cooperation in their part of the world.

At a summit in Brussels, the 28 European Union leaders — 22 of them from nations that also are members of NATO — agreed to jointly develop or purchase military equipment such as drones.

"The objective is to deliver capabilities, ensure a competitive, innovative and balanced basis for Europe's defense industry across the EU," they said in a statement.

EU countries plan to draw up criteria and binding commitments over the next three months for setting their defense cooperation goals in stone instead of relying on the vaguer promises of the past.

The leaders also agreed to use EU funds to finance Europe's battlegroups — small, expeditionary forces that can be deployed quickly to crisis hot spots.

The battlegroups were established in 2007. They never have been used, mostly because countries participating in them would have to foot the bill if they were deployed.

The leaders also welcomed plans to set up a common European defense fund that is expected to generate about €5 billion (U.S. $5.6 billion) a year from 2020 to invest in developing military equipment.

While the moves are modest in comparison to NATO, they mark a sea change in the way the EU thinks about defense, faced with an increasingly belligerent Russia and an unpredictable partner in Washington.

"I am not going to say this is a historic moment, because you would laugh in my face, but it is an important step," Belgian Prime Minister Charles Michel said.